Method for manufacturing semiconductor device and semiconductor substrate

ABSTRACT

A method for manufacturing a semiconductor device includes the steps of forming a fixing layer, coupling a third substrate different from the first substrate and the second substrate to the fixing layer, separating the semiconductor thin film layer from the first substrate by moving the third substrate away from the base material substrate with the third substrate coupled to the coupling region, and bonding the semiconductor thin film layer to the second substrate after separation from the base material substrate, wherein the forming the fixing layer forms the fixing layer having a thickness such lhat a crack is generated between the fixing layer formed on the first substrate and the fixing layer formed on a side surface of the semiconductor thin film layer by a force for moving the third substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 17/002,781, filed on Aug. 26, 2020, which is acontinuation application of International Application numberPCT/JP2018/012370, filed on Mar. 27 2018, which claims priority under 35U.S.C § 119(a) to Japanese Patent Application No. 2018-035221, filed onFeb. 28, 2018. The contents of these applications are incorporatedherein by reference in their entirety.

BACKGROUND

This invention relates to a method for manufacturing a semiconductordevice. Japanese Patent No. 3813123 discloses a technique of detaching asemiconductor epitaxial layer from a base material substrate andtransferring the semiconductor epitaxial layer to another substrate.

FIG. 22 is a figure for explaining the prior art. FIG. 22 shows asemiconductor structure composed of a base material substrate 3001, asacrificial layer 3002, a semiconductor epitaxial layer 3003, and asupport body 3004. The sacrificial layer 3002 is provided between thesemiconductor epitaxial layer 3003 and the base material substrate 3001,and is smaller than the semiconductor epitaxial layer 3003 due toetching. The reference numeral 3010 indicates a region where thesacrificial layer 3002 has been etched away.

The support body 3004 has the same horizontal cross section as thesemiconductor epitaxial layer 3003, and is provided on the semiconductorepitaxial layer 3003. The support body 3004 is a member for supportingthe semiconductor epitaxial layer 3003 when detaching the semiconductorepitaxial layer 3003 from the base material substrate 3001. In theconventional technique shown in FIG. 22 , the sacrificial layer 3002 isetched away to peel off the semiconductor epitaxial layer 3003 from thebase material substrate 3001.

In the conventional technique shown in FIG. 22 , the semiconductorepitaxial layer 3003 and the support body 3004 are peeled off from thebase material substrate 3001 at the lime when the sacrificial layer 3002is completely etched away. Therefore, there is a problem that thesemiconductor epitaxial layer 3003 has to be transferred and placed in atemporary place different from the base material substrate 3001 at thetime when the sacrificial layer 3002 is completely etched away and thesemiconductor epitaxial layer 3003 is separated from the base materialsubstrate 3001.

SUMMARY

The present invention focuses on this point, and an object thereof is toimprove the efficiency of a method for manufacturing a semiconductordevice by bonding a semiconductor epitaxial layer to another substrate.

A method for manufacturing a semiconductor device in which asemiconductor thin film layer formed on a first substrate is separatedfrom the first substrate and bonded onto a second substrate differentfrom the first substrate, the method comprises steps of forming a fixinglayer that is a thin film for coupling at least a portion of a mainsurface of the semiconductor thin film layer on the side opposite to afirst substrate side and at least a portion of the surface of the firstsubstrate on a semiconductor thin film layer side, coupling a thirdsubstrate different from the first substrate and the second substrate tothe coupling region that is at least portions of the fixing layer andthe semiconductor thin film layer, separating the semiconductor thinfilm layer from the first substrate by moving the third substrate awayfrom the first substrate with the third substrate coupled to thecoupling region, and bonding the semiconductor thin film layer to thesecond substrate after separation from the first substrate, wherein theforming the fixing layer forms the fixing layer having a thickness suchthat a crack is generated between the fixing layer formed on the firstsubstrate and the fixing layer formed on a side surface of thesemiconductor thin film layer by a force for moving the third substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a figure for explaining a process of detaching asemiconductor thin film layer island from a base material substrate.

FIG. 1B is a figure for explaining the process of detaching thesemiconductor thin film layer island from the base material substrate.

FIG. 1C is a figure for explaining the process of detaching thesemiconductor thin film layer island from the base material substrate.

FIG. 1D is a figure for explaining the process of detaching thesemiconductor thin film layer island from the base material substrate.

FIG. 1E is a figure for explaining the process of detaching thesemiconductor thin film layer island from the base material substrate.

FIG. 2A shows a pick-up substrate which is a third substrate.

FIG. 2B shows an A-A-line cross section of the pick-up substrate shownin FIG. 2A.

FIG. 2C shows a variation of the pick-up substrate.

FIG. 3A schematically shows a process of separating the semiconductorthin film layer island from the base material substrate.

FIG. 3B schematically shows the process of separating the semiconductorthin film layer island from the base material substrate.

FIG. 3C schematically shows the process of separating the semiconductorthin film layer island from the base material substrate.

FIG. 3D schematically shows a process of bonding the separatedsemiconductor thin film layer island to a destination substrate.

FIG. 3E schematically shows the process of bonding the separatedsemiconductor thin film layer island to a destination substrate.

FIG. 3F schematically shows the process of bonding the separatedsemiconductor thin film layer island to a destination substrate.

FIG. 4A schematically shows a process of transferring a plurality ofsemiconductor thin film layer islands.

FIG. 4B schematically shows the process of transferring the plurality ofsemiconductor thin film layer islands.

FIG. 4C schematically shows the process of transferring the plurality ofsemiconductor thin film layer islands.

FIG. 4D schematically shows the process of transferring the plurality ofsemiconductor thin film layer islands.

FIG. 4E schematically shows the process of transferring the plurality ofsemiconductor thin film layer islands.

FIG. 5A is a figure for explaining a method for transferring theplurality of semiconductor thin film layer islands.

FIG. 5B is a figure for explaining the method for transferring theplurality of semiconductor thin film layer islands.

FIG. 5C is a figure for explaining the method for transferring theplurality of semiconductor thin film layer islands.

FIG. 5D is a figure for explaining the method for transferring theplurality of semiconductor thin film layer islands.

FIG. 5E is a figure for explaining the method for transferring theplurality of semiconductor thin film layer islands.

FIG. 6 shows a process flow of a method for manufacturing asemiconductor device according to the present embodiment.

FIG. 7A is an example of a variation of the method for manufacturing thesemiconductor device.

FIG. 7B is the example of the variation of the method for manufacturingthe semiconductor device.

FIG. 7C is the example of the variation of the method for manufacturingthe semiconductor device.

FIG. 7D shows an A-A-line cross section of the semiconductor device.

FIG. 8A shows a structure of the semiconductor device.

FIG. 8B shows the structure of the semiconductor device.

FIG. 8C shows the structure of the semiconductor device.

FIG. 9A shows a variation of a shape of a fixing layer.

FIG. 9B shows a variation of the shape of the fixing layer.

FIG. 9C shows a variation of the shape of the fixing layer.

FIG. 9D shows a variation of the shape of the fixing layer.

FIG. 10 schematically illustrates a semiconductor epitaxial wafer, inwhich a semiconductor epitaxial layer is formed on a wafer used as abase material substrate.

FIG. 11A shows a relation between an angle θ and an etching rate of aSi(111) substrate surface region in a direction perpendicular to thelonger side of the semiconductor thin film layer island.

FIG. 11B is a figure for explaining the angle θ.

FIG. 12 shows hexagonal semiconductor thin film layer islands.

FIG. 13A is a photomicrograph of a GaN semiconductor thin film layerisland formed on the Si(111) substrate as a base material substrate.

FIG. 13B is a photomicrograph of the GaN semiconductor thin film layerisland in which the orientation of the longer side of the semiconductorthin film layer island with respect to a crystal orientation of the basematerial substrate is different from that shown in FIG. 13A.

FIG. 14 is a photomicrograph of the semiconductor thin film layer islandbeing bonded to the destination substrate, the longer side of thesemiconductor thin film layer island being substantially parallel to a<1-100> orientation.

FIG. 15A is a figure for explaining a method for easily breaking thefixing layer.

FIG. 15B is a figure for explaining the method for easily breaking thefixing layer.

FIG. 16 is a photomicrograph showing results of observing a separationstate of the fixing layer in an actual experiment.

FIG. 17 is a photomicrograph of a state where the semiconductor thinfilm layer island separated from the base material substrate is bondedto the destination substrate.

FIG. 18A shows an example of the fixing layer having a region extendingin a transverse orientation.

FIG. 18B shows an example of the fixing layer having a region extendingin a transverse orientation.

FIG. 19A is an overhead view of the base material substrate and thesemiconductor thin film layer island and schematically shows a statewhere the semiconductor thin film layer formed on the base materialsubstrate is divided into individual semiconductor thin film layerislands.

FIG. 19B shows a cross section of the base material substrate and thesemiconductor thin film layer island.

FIG. 20A is an overhead view of a semiconductor device including asemiconductor thin film layer having a step structure that is notexposed to an outer periphery of the semiconductor thin film layerisland.

FIG. 20B shows an A-A-line cross-section of the semiconductor deviceshown in FIG. 20A.

FIG. 20C shows a B-B-line cross-section of the semiconductor deviceshown in FIG. 20A.

FIG. 21A is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21B is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21C is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21D is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21E is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21F is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21G is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21H is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 21I is a figure for explaining a method for manufacturing asemiconductor device.

FIG. 22 is a figure for explaining the prior art.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be described through exemplaryembodiments of the present invention, hut the following exemplaryembodiments do not limit the invention according to the claims, and notall of the combinations of features described in the exemplaryembodiments are necessarily essential to the solution means of theinvention.

<An Outline of a Method for Manufacturing a Semiconductor Device>

In a method for manufacturing a semiconductor device according to thepresent embodiment, a semiconductor thin film layer island on a basematerial substrate, which is a first substrate, is transferred to adestination substrate, which is a second substrate, therebymanufacturing a semiconductor device having the destination substrateand a semiconductor thin film layer. The “semiconductor thin film layerisland” is a region of the semiconductor thin film layer having the sizesame as the base material substrate, or a region of the semiconductorthin film layer smaller than the base material substrate. A singlesemiconductor thin film layer island or a plurality of semiconductorthin film layer islands may be formed on a single base materialsubstrate.

The method for manufacturing the semiconductor device according to thepresent embodiment is characterized in that a fixing layer supportingthe semiconductor thin film layer island separated from the basematerial substrate is formed, and so the semiconductor thin film layerisland that is separated from the base material substrate to betransferred to the destination substrate can be maintained in a stablestale above the base material substrate. Thus, it is possible totransfer the separated semiconductor thin film layer island to thesecond substrate by connecting the semiconductor thin film layer islandto an organic material layer formed on a pick-up substrate, which is athird substrate, and then separating the semiconductor thin film layerisland from the base material substrate.

<A Process of Detaching the Semiconductor Thin Film Layer Island fromthe Base Material Substrate>

FIGS. 1A to 1E are figures for explaining a process of detaching thesemiconductor thin film layer island from the base material substrate.Hereinafter, an outline of the process of detaching the semiconductorthin film layer island from the base material substrate will bedescribed while referencing FIGS. 1A to 1E.

First, as shown in FIG. 1A, a layer to be removed 102 is formed on abase material substrate 101, which is the first substrate, and asemiconductor thin film layer 104, which is a semiconductor epitaxiallayer, is formed on the layer to be removed 102. The layer to be removed102 is a region to be removed by etching in a later step.

For example, the layer to be removed 102 is formed of a material havingan etching rate different from that of the base material substrate 101and the semiconductor thin film layer 104 when being etched using apredetermined etching method (wet etching using a predetermined etchantor dry etching using a predetermined gas). The layer to be removed 102may be formed of a material equivalent to that of the base materialsubstrate 101. For example, the layer to be removed 102 may be a partialregion in the vicinity of the surface of the base material substrate101.

The semiconductor thin film layer 104 is, for example, a semiconductorthin film layer formed by epitaxial growth or a semiconductor thin filmlayer formed by wafer bonding. The semiconductor thin film layer 104 maybe a semiconductor thin film layer formed by other methods.

The semiconductor thin film layer 104 is, for example, a groupd III-Vcompound semiconductor material (such as GaAs, AlGaAs, InGaAs, InP, andInAlGaP), a group III nitride semiconductor material (such as GaN, InN,AlGaN, InGaN, and AlN), a dioxide semiconductor material (such as ZnOand Ga₂O₃), a group IV compound semiconductor material (such as SiC), adiamond, Si, or SiGe. The base material substrate 101 is, for example, agroup III-V compound semiconductor material substrate (such as a GaAssubstrate and an InP substrate), a group III nitride semiconductormaterial substrate (such as a GaN substrate), an oxide semiconductormaterial substrate (such as a ZnO substrate and a Ga₂O₃ substrate), agroup IV compound semiconductor substrate (such as SiC), a diamondsubstrate, or Si, SiGe.

Subsequently, as shown in FIG. 1B, the semiconductor thin film layer 104is divided into a plurality of island regions to form a semiconductorthin film layer island 108 (hereinafter, the “semiconductor thin filmlayer island 108” may be referred to as the “island 108”). The shape ofthe island 108 is not limited, but the following description exemplifiesa case where the island 108 is rectangular. The island 108 may be, forexample, square or hexagonal. It should be noted that, instead ofdividing the semiconductor thin film layer 104 into a plurality ofisland regions, a single island 108 or a plurality of islands 108 may beformed by selectively growing the semiconductor thin film layer 104 onthe base material substrate 101.

Further, a method for forming the island 108 is arbitrary, and can beexemplified by the following methods.

1) A method for forming the island 108 by processing a semiconductorthin film layer 104 with a photolithographic/etching process

2) A method for forming the island 108 by selectively growing thesemiconductor thin film layer 104 on the base material substrate 101

3) A method for forming the island 108 by laterally growing thesemiconductor thin film layer 104 in the lateral direction (horizontaldirection) on the base material substrate 101

Hereinafter, one semiconductor thin film layer island 108 out of theplurality of semiconductor thin film layer islands 108 will bedescribed. In this process, the island 108 may be formed including thelayer to be removed 102, as shown in FIG. 1B. A region of the layer tobe removed 102 included in the island 108 is a region to be removed 106shown in FIG. 1B.

Subsequently, a fixing layer 110 is formed as shown in FIGS. 1C and 1D.The fixing layer 110 is a thin film lhat couples i) at lease a portionof a main surface of the island 108 on the side opposite the basematerial substrate 101 side and ii) at least a portion of the surface ofthe base material substrate 101 on the island 108 side. The fixing layer110 has a shape, for example, extending from the upper surface of theisland 108 to the base material substrate 101, but the fixing layer 110may have other shapes, as long as the fixing layer 110 can couple theisland 108 and the base material substrate 101. For example, the fixinglayer 110 may be a film that couples the both of shorter side surfacesof the island 108 and the base material substrate 101. The fixing layer110 may be a film that couples the both of longer side surfaces of theisland 108 and the base material substrate 101. The fixing layer 110 maybe composed of two thin films that couple the both of shorter sidesurfaces of the island 108 and the base material substrate 101. Further,the fixing layer 110 may be a thin film extending via both of the longerside surfaces of the island 108 so as to extend across the island 108,with the base material substrate 101 as a starting point and an endingpoint. In addition, the fixing layer 110 may be parallel to the side ofthe island 108, and may be formed to extend in a direction differentfrom the orientation of the side of the island 108.

If the fixing layer 110 is formed to extend in the longitudinalorientation of the island 108, the fixing layer 110 is formed as followsin the process of forming the fixing layer 110: 1) the fixing layer 110is formed to extend between both ends of the semiconductor thin filmlayer 104 in a first orientation (for example, an orientation connectingboth side surfaces of the semiconductor thin film layer 104 that have ahigher coverage by the fixing layer) on the main surface of thesemiconductor thin film layer 104, and 2) the fixing layer 110 is formedsuch that the semiconductor thin film layer 104 is exposed in at leastsome regions on both side surfaces of the semiconductor thin film layer104 in a second orientation orthogonal to the first orientation. If theisland 108 is rectangular, the coverage of the longer side surfaces ofthe island 108 by the fixing layer 110 is less than the coverage of theshorter side surfaces by the fixing layer 110. This makes it possible toshorten the time required, when the etching described further below isperformed, for removing i) a partial region of the island 108 or thebase material substrate 101, or ii) a partial region of the layerbetween the island 108 and the base material substrate 101 in order toseparate the island 108 and the base material substrate 101.

FIG. 1D is an overhead view corresponding to FIG. 1C. The fixing layer110 serves to anchor the island 108 above the base material substrate101 so that the position of the island 108 on the base materialsubstrate 101 does not change at least directly below the island 108.The fixing layer 110 is a thin film layer made of a material havingetching resistance against an etching means for etching the region to beremoved 106.

As a material of the fixing layer 110, an inorganic insulating film suchas an oxide film (such as Si_(x)O_(y), Si_(x)O_(y)N_(z), Al_(x)O_(y),and Al_(x)O_(y)N_(z)) and a nitride film (such as Si_(x)N_(y) andAl_(x)N_(y)) can be used, for example. The inorganic insulating film maybe a single layer or a stack of different materials. For example, adesired fixing layer 110 can be formed by forming an inorganicinsulating film using a Chemical Vapor Deposition (CVD) method andremoving a pan of the inorganic insulating film by a standardphotolithography and etching process. An organic film (such as aphotosensitive coating film and a photosensitive organic sheet) may beused as the material of the fixing layer 110 as long as the organic filmis resistant to the predetermined etching means for etching the regionto be removed 106.

The optimum thickness of the fixing layer 110 can be selected accordingto the size and thickness of the semiconductor thin film layer island108. The thickness of the fixing layer 110 is, for example, less thanthe thickness of the semiconductor thin film layer island 108 (that is,the thickness of the semiconductor thin film layer 104 formed on thebase material substrate 101). The fixing layer 110 preferably has athickness such that the fixing layer 110 formed on the side surfaces ofthe semiconductor thin film layer 104 is cut off from the fixing layer110 formed on the base material substrate 101 by a force for moving apick-up substrate 200, which is a third substrate to be described later,in a direction of being separated from the base material substrate 101,while the pick-up substrate 200 is coupled to at least portions of thecoupling regions of the fixing layer 110 and the semiconductor thin filmlayer 104.

The semiconductor thin film layer island 108 shown in FIG. 1D has sideswith lengths L1 and L2, where L1>L2. The fixing layer 110 has a firstregion covering the upper surface of the island 108, a second regioncovering the right side surface of the island 108, and a third regioncovering the left side surface of the island 108. The fixing layer 110further has regions covering the base material substrate 101 beyond thesecond region and the third region. In the example shown in FIG. 1D, thefixing layer 110 does not cover the longer side surfaces (that is, thesurfaces of the side having the length L1) and covers a portion of theshorter side surfaces (that is, the surfaces of the side having thelength L2), out of the four side surfaces of the island 108.

Subsequently, as shown in FIG. 1E, a void 103 is formed by removing i) apartial region of the island 108 or the base material substrate 101 orii) a partial region of a layer to be removed between the island 108 andthe base material substrate 101. For example, at least a region of theisland 108, which is connected to the base material substrate 101 thatis directly below the island 108, is etched away, thereby forming thevoid 103 at least in the region directly below the island 108 betweenthe island 108 and the base material substrate 101. In forming the void103, it is desirable to use an etchant or etching gas such that theetching rate of the island 108 for the etchant or the etching gas issmaller than that of the region to be removed 106.

In the above etching process, for example, if the etching of the layerto be removed proceeds isotropically and the etching rate is independentof the direction, the etching in the direction perpendicular to thelonger side of the island 108 is completed faster than the etching inthe direction perpendicular to the shorter side, since the distance inthe direction perpendicular to the longer side is shorter than distancein the direction perpendicular to the shorter side. Therefore, theetching can be completed more quickly to form the void 103 by i) leavingthe longer side surfaces uncovered or ii) forming the fixing layer 110such that the coverage of the longer side by the fixing layer 110 issmaller than the coverage of the shorter side by the fixing layer 110.This makes it possible to reduce the risk of the island 108 beingdamaged by etching in the etching process for removing the region to beremoved 106.

It should be noted that the void 103 is formed by removing the layer tobe removed 102 by etching in the above description, but the void may beformed by removing the surface region of the base material substrate 101by anisotropic etching without forming the layer to be removed 102.

If the void is formed by removing the region of the surface of the basematerial substrate 101 by anisotropic etching, both side surfaces in anorientation having a large etching rate are preferably set to be in thesecond orientation in the process of forming the fixing layer. Both ofthese side surfaces in the second orientation may be entirely exposed,or partial regions thereof may be covered by the fixing layer 110.Further, the fixing layer 110 is preferably formed in a manner in whichthe coverage of both side surfaces of the semiconductor thin film layer104 in the second orientation by the fixing layer 110 extending in thesecond orientation is less than the coverage of both side surfaces ofthe semiconductor thin film layer 104 in the first direction by thefixing layer 110 extending in the first direction. This makes itpossible to form the void 103 easily by etching.

In the above description, the semiconductor thin film layer island 108is rectangular, but the island 108 may be square in the following cases.

1) A case where the semiconductor thin film layer is separated from thebase material substrate by removing the layer to be removed 102 byetching

2) A case where the anisotropic etching is used to remove the surfaceregion of the base material substrate 101

3) A case where the island 108 is very small (for example, 20 μm orless)

<A Process of Separating the Semiconductor Thin Film Layer Island 108>

FIG. 2A shows the pick-up substrate 200, which is a third substrate, forseparating the semiconductor thin film layer island 108 from the basematerial substrate 101. FIG. 2B shows an A-A-line cross section of thepick-up substrate shown in FIG. 2A. As shown in FIG. 2B, the pick-upsubstrate 200 has a base substrate 201 and a pick-up bump 202 made of anorganic material formed on the base substrate 201. As the base substrate201. for example, quartz, sapphire, a transparent substrate such asglass, a semiconductor substrate such as Si, a ceramic substrate, or ametal substrate or the like can be selected. The base substrate 201 maybe made of a single material or a laminated material. Further, the basesubstrate 201 may be a substrate having a surface coated with othermaterials.

The pick-up hump 202 is, for example, an organic material layer, and canbe formed by performing a standard photolithography process on aphotosensitive organic material applied onto the base substrate 201. Theorganic material layer may be formed by applying a coating on a pick-upbase substrate using, for example, a spin-coating method, a dip method,or the like, and may be formed by attaching an organic material film onthe pick-up base substrate.

The structure of the pick-up substrate can be varied depending on theshape and size of the island 108 to be picked up. For example, thepick-up substrate may have another structure interposed between the basesubstrate 201 and the pick-up bump 202. Further, the pick-up substratedoes not need to have the pick-up bump 202 that matches the shape of theisland 108 to be separated from the base material substrate 101, and mayhave a flat pick-up layer 204 having an area larger than that of theisland 108, as in the pick-up substrate 200′ shown in FIG. 2C.

FIGS. 3A to 3C schematically show a process of separating the island 108from the base material substrate 101 by using the pick-up substrate 200.

First, the pick-up bump 202 of the pick-up substrate 200 is aligned withthe island 108 as shown in FIG. 3A. Specifically, the pick-up substrate200 is disposed at a position so that at least a partial region of thepick-up bump 202 overlaps with at least partial regions of the fixinglayer 110 and the island 108.

Next, the pick-up bump 202 is brought into contact with or pressedagainst at least the partial regions of the fixing layer 110 and theisland 108 as shown in FIG. 3B. As a result, the pick-up bump 202 iscoupled to at least the partial regions of the fixing layer 110 and theisland 108. When a downward force is applied to the pick-up substrate200 contacting the fixing layer 110 and the island 108 while the void103 is formed between the island 108 and the base material substrate101, the fixing layer 110 cracks or breaks in the vicinity of a boundaryline (a broken line in FIG. 3B) between the island 108 and the void 10.

As shown in FIG. 3C, the pick-up substrate 200 coupled to the partialregion of the fixing layer 110 is pulled up in a state where the fixinglayer 110 cracks or breaks, thereby breaking the fixing layer 110 into afixing layer 114 adjoining the island 108 and a fixing layer 112adjoining the base material substrate 101, and the fixing layer 114,which is the partial regions of the semiconductor thin film layer island108 and the fixing layer 110, can be separated from the base materialsubstrate 101.

It should be noted that the island 108 may be separated from the basematerial substrate 101 in a state where the surface of the island 108facing the base material substrate 101 is accompanied by a semiconductorlayer of a material different from the semiconductor thin film layer104. For example, the island 108 separated from the base materialsubstrate 101 may be accompanied by a mask film or a dielectric layerprovided on the base material substrate 101 for selectively growing orlaterally growing the semiconductor thin film layer 104.

[A Process of Bonding the Semiconductor Thin Film Layer Island 108 toAnother Substrate]

FIGS. 3D to 3F schematically show a process of bonding the separatedsemiconductor thin film layer island 108 to a destination substrate 301.As shown in FIG. 3D, a structure 210 with a state in which the island108 and the fixing layer 114 are coupled to the pick-up substrate 200 isaligned at a predetermined position above the destination substrate 301which is the second substrate.

Thereafter, a surface 308 of the island 108 positioned below the fixinglayer 114 in the structure 210 is pressed against the destinationsubstrate 301 as shown in FIG. 3E, thereby bonding the island 108 to thedestination substrate 301. Prior to the process of pressing the island108 against the destination substrate 301, surfaces to be bonded (asurface 302 of the destination substrate 301 and the surface 308 of thesemiconductor thin film layer island 108) may be appropriatelysurface-treated.

Next, the pick-up bump 202 and the base substrate 201 are removed fromthe fixing layer 114 as shown in FIG. 3F. For example, the pick-up bump202 is dissolved by immersing the pick-up bump 202 in a chemicalsolution such as an organic solvent that dissolves an organic materialconstituting the pick-up bump 202, thereby separating the fixing layer114 and the base substrate 201 from each other.

If the connection between the destination substrate 301 and the island108 becomes strong in a step of pressing the island 108 against thedestination substrate 301, the pick-up substrate 200 may be pulled upbefore the chemical solution such as an organic solvent dissolves thepick-up bump 202. In this case, a step of cleaning the destinationsubstrate 301 to which the island 108 is bonded with the chemicalsolution such as an organic solvent may be added after pulling up thepick-up substrate 200.

It should be noted that a predetermined device structure or a part of adevice structure may be formed on the above-described island 108 bondedto the destination substrate 301 before forming the fixing layer 110.

Further, after bonding the island 108 onto the destination substrate 301described above, the fixed layer 110 may be processed and an interiayerinsulating film may be formed on the semiconductor thin film layer suchthat a wiring structure for forming an electrical connection with anexternal structure is formed.

Further, the island 108 is bonded to the surface of the destinationsubstrate 301 in the above description, but other layer (such as aninorganic material thin film layer and an organic material thin filmlayer) may be provided between the destination substrate 301 and theisland 108. In addition, a heat treatment step may be provided after thebonding step.

Further, when bonding the island 108 separated from the base materialsubstrate 101 to the destination substrate 301, the surface of the sideof the island 108 to be bonded to the destination substrate 301 may beaccompanied by a semiconductor layer made of a material different fromthat of the semiconductor thin film layer 104. For example, the island108 accompanied by a mask film or a dielectric layer for selectivelygrowing or laterally growing the semiconductor thin film layer 104provided on the base material substrate 101 may be bonded to thedestination substrate 301.

<A Method for Transferring a Plurality of Islands 108>

The above explanation discloses the method for transferring one singlesemiconductor thin film layer island 108, but the method formanufacturing the semiconductor device according to the presentembodiment also allows transferring a plurality of semiconductor thinfilm layer islands 408 a, 408 b, and 408 c as shown in FIGS. 4A to 4E.When collectively separating the plurality of islands 408 a, 408 b, and408 c from a base material substrate 401, a pick-up substrate 420including a plurality of pick-up bumps 422 a, 422 b, and 422 ccorresponding to the plurality of islands 408 a, 408 b, and 408 c isprepared. Then, the pick-up substrate 420 is brought into contact withor pressed against fixing layers 410 a, 410 b, and 410 c and the islands408 a, 408 b, and 408 c with the same process as described above toseparate the plurality of islands 408 a, 408 b, and 408 c from the basematerial substrate 401, and the plurality of islands 408 a, 408 b, and408 c are bonded onto a destination substrate 451.

FIGS. 4A to 4F schematically show the process of transferring theplurality of islands 408 a, 408 b, and 408 c. In FIGS. 4A to 4E, thebase material substrate 401, a plurality of voids 403 a, 403 b, and 403c, the plurality of islands 408 a, 408 b, and 408 c, the plurality offixing layers 410 a, 410 b, and 410 c, a plurality of fixing layers 414a, 414 b, and 414 c, a plurality of fixing layers 416 a, 416 b, and 416c, the pick-up substrate 420, a base substrate 421, the plurality ofpick-up bumps 422 a, 422 b, and 422 c, a structure 430, and thedestination substrate 451 respectively correspond to the base materialsubstrate 101, the void 103, the island 108, the fixing layer 110, thefixing layer 112, the fixing layer 114, the pick-up substrate 200, thebase substrate 201, the pick-up bump 202, the structure 210, and thedestination substrate 301 in FIGS. 3A to 3F. A pick-up substrate, asshown in FIG. 2C, that does not have a pick-up bump but includes apick-up layer made of an organic material may be used when separatingthe plurality of islands 408 a, 408 b, and 408 c from the base materialsubstrate 401.

[Transfer of the Plurality of Semiconductor Thin Film Layer Islands]

FIGS. 5A to 5E are figures for explaining a method for transferring theplurality of semiconductor thin film layer islands. In FIGS. 5A to 5E, abase material substrate 501, a plurality of voids 503 a, 503 b, and 503c, a plurality of islands 508 a, 508 b, and 508 c, a plurality of fixinglayers 510 a, 510 b, and 510 c, a plurality of fixing layers 514 a and514 c, a plurality of fixing layers 516 a and 516 c, a pick-up substrate520, a base substrate 521, a plurality of pick-up bumps 522 a and 522 c,a structure 530, a destination substrate 531, and a surface 551respectively correspond to the base material substrate 101, the void103, the island 108, the fixing layer 110, the fixing layer 114, thefixing layer 112, the pick-up substrate 200, the base substrate 201, thepick-up bump 202, the structure 210, the destination substrate 301, andthe surface 302 in FIGS. 3A to 3F. Hereinafter, a method for selectingand transferring some of the islands to the destination substrate out ofthe plurality semiconductor thin film layer islands formed on the basematerial substrate will be described.

As shown in FIG. 5A, after the voids 503 a to 503 c are formed at leastdirectly below the semiconductor thin film layer islands, the pick-upbumps 522 a and 522 c made of an organic material are provided on thebase substrate 521 of the pick-up substrate 520 only at positionscorresponding to the selected semiconductor thin film layer islands 508a and 508 c. Subsequently, the pick-up bumps 522 a and 522 c are broughtinto contact with or pressed against the islands 508 a and 508 c, andthe pick-up substrate 520 is coupled to the selected islands 508 a and508 c. FIG. 5B is an overhead view of FIG. 5A, and FIG. 5A is theA-A-line cross section of FIG. 5B.

Next, the pick-up substrate 520 coupling the selected islands 508 a and508 c is pulled up, and only the selected islands 508 a and 508 c areseparated from the base substrate 501, as shown in FIG. 5C. FIG. 5Cshows the pick-up substrate 520 lifting the selected islands 508 a and508 c. A non-selccled island 508 b remains on the base materialsubstrate 501 as shown in FIG. 5C.

Next, a structure (the structure 530 shown in FIG. 5C), in which thepick-up substrate 520 with the island 508 a, the island 508 c, thefixing layer 514 a, and the fixing layer 514 c are coupled, is disposedat a predetermined position on the destination substrate 531 as shown inFIG. 5D. Subsequently, a surface 558 a and a surface 558 c of the island508 a and the island 508 c, on the side opposite to the fixing layer 514a and the fixing layer 514 c, arc pressed against the surface 551 of thedestination substrate 531, and the selected islands 508 a and 508 c arebonded to the destination substrate 531.

Next, the pick-up bump 522 a, the pick-up bump 522 c, and the basesubstrate 521 are removed from the destination substrate 531, therebymanufacturing a semiconductor device, in which the semiconductor thinfilm layer islands 508 a and 508 c are bonded to the destinationsubstrate 531, as shown in FIG. 5E.

[A Process Flow of the Method for Manufacturing the SemiconductorDevice]

FIG. 6 shows a process flow of the method for manufacturing thesemiconductor device according to the present embodiment. As shown inFIG. 6 , in the method of manufacturing the semiconductor deviceaccording to the present embodiment, the selected islands 508 a and 508c may be separated from the base material substrate 501 and bonded tothe destination substrate 531 by using the pick-up substrate 520 havingthe pick-up bumps 522 a and 522 c made of an organic materialcorresponding to the predetermined selected semiconductor thin filmlayer islands 508 a and 508 c on the base material substrate 501. Thismakes it possible to select desired islands 508 a and 508 c out of theplurality of islands 508 a, 508 b, and 508 c on the base materialsubstrate 501 and to bond the selected islands 508 a and 508 c to thedestination substrate 531.

It is obvious that various modifications can be made to the method forseparating the desired islands 508 a and 508 c out of the plurality ofislands 508 a, 508 b, and 508 c on the base substrate 501.

[Effects of the Method for Manufacturing the Semiconductor Device of thePresent Embodiment]

According to the method for manufacturing the semiconductor devicedescribed above, the semiconductor thin film layer island 108 fixed onthe base material substrate 101 by the fixing layer 110 is separatedfrom the base material substrate 101 by using the pick-up substrate 200with the pick-up bump 202 made of an organic material formed on the basesubstrate 201 by photolithography, and the semiconductor thin film layerisland 108 coupled to the pick-up substrate 200 is bonded to thedestination substrate 301 by pressure. This enables the semiconductorthin film layer 104 separated from the base material substrate 101 to beeasily transferred to another substrate.

Further, it is also apparent to those skilled in the art that thepick-up substrate 200 including the pick-up bump 202 having the optimumshape and size can be easily produced to match the semiconductor thinfilm layer island 108 to be separated from the base material substrate101. According to the method for manufacturing the semiconductor deviceof the present embodiment, the pick-up substrate 200, which can beeasily produced, separates the semiconductor thin film layer island 108from the base material substrate 101 and bonds the island 108 to thedestination substrate 301, and so the semiconductor thin film layerisland 108 can be transferred at a low cost.

Further, the base substrate 201 can be repeatedly used since the pick-upbump 202 made of an organic material and the base substrate 201 of thepick-up substrate 200 are removed from the destination substrate 301after the semiconductor thin film layer island 108 is bonded to thedestination substrate 301.

Furthermore, forming the fixing layer 110 extending in the longitudinalorientation of the island 108 as described above produces the followingeffects.

(1) A device structure, such as wiring and an electrode formed on thesemiconductor thin film layer surface and the semiconductor thin filmlayer island 108, can be protected in case an etchant or etching gas isused in the process of forming the void between the semiconductor thinfilm layer island 108 and the base material substrate 101.

(2) The amount of warpage of the semiconductor thin film layer island108 due to stress applied to the semiconductor thin film layer island108 can be reduced in the process from forming the void between thesemiconductor thin film layer island 108 and the base material substrate101 to bonding the island 108 on the destination substrate 301. If thewarpage of the semiconductor thin film layer island 108 is reduced byreducing the stress as described above, for example, the fixing layer110 easily retains the semiconductor thin film layer island 108 abovethe base material substrate 101 in a slate where the void is formed. Asa result, it is easy to separate the semiconductor thin film layerisland 108 by using the pick-up substrate 200 as well as to retain thesemiconductor thin film layer island 108 on the destination substrate301 in the bonding process onto the destination substrate 301.

(3) The fixing layer 110 can be used as an interlayer insulating film orthe like between a wiring layer and the semiconductor thin film layer ina device forming process after bonding the island 108 onto thedestination substrate 301.

(4) A disconnection of the wiring layer can be prevented at a leveldifference portion that exists if the fixing layer 110 is discontinuouswhen forming the wiring layer on the fixing layer 110 in the deviceforming process after bonding the island 108 onto the destinationsubstrate 301.

(5) It is easy to ensure uniformity of the characteristics of thesemiconductor device formed by using the semiconductor thin film layerisland 108 bonded onto the destination substrate 301. Because thesurface of the semiconductor thin film layer island 108 is coated by acontinuous fixing layer 110, for example, the intensity distribution oflight emitted from the upper surface of the light emitting devicebecomes uniform. If the surface of the semiconductor thin film layerisland 108 is covered by a discontinuous fixing layer 110, the lightintensity changes in a discontinuous region of the fixing layer 110.

It should be noted that the semiconductor thin film layer has arectangular shape in the above description, but the semiconductor thinfilm layer may have a circular shape or a complicated shape other thanthe rectangular shape. Further, although a simple semiconductor thinfilm layer having no device structure is exemplified (illustrated) inthe above description, the semiconductor thin film layer may have adevice structure. Furthermore, the semiconductor thin film layer surfacedoes not have to be flat, and may be provided with a thin film structureof a dielectric material or a metal material corresponding to a devicestructure.

[A Variation of the Method for Manufacturing the Semiconductor Device]

FIGS. 7A to 7D show an example of a variation of the method formanufacturing the semiconductor device. In FIGS. 7A to 7D, a basematerial substrate 701, a plurality of voids 703 a, 703 b, 703 c, and703 d, a plurality of islands 708 a, 708 b, 708 c, 708 d, 718 a, and 718b, a plurality of fixing layers 705 a, 705 b, 705 c, and 705 d, aplurality of fixing layers 714 a and 714 b, a pick-up substrate 710, abase substrate 711, a pick-up layer 712, and a destination substrate 731respectively correspond to the base material substrate 101, the void103, the island 108, the fixing layer 110, the fixing layer 114, thepick-up substrate 200, the base substrate 201, the pick-up layer 204,and the destination substrate 301 in FIG. 2C and FIGS. 3A to 3F. Asshown in FIGS. 7A and 7B (FIG. 7B is an A-A-line cross section of FIG.7A), a plurality of predetermined islands out of the plurality ofsemiconductor thin film layer islands (for example, the islands 708 a,708 b, 708 c, 708 d, 718 a, and 718 b) on the base material substrate701 can be separated from the base material substrate. Further, as shownin FIGS. 7C and 7D (FIG. 7D is an A-A-line cross section of FIG. 7C),the islands (708 a, 708 b, 718 a, and 718 b in FIG. 7C) separated fromthe base material substrate 701 can be well bonded to predeterminedpositions on the destination substrate 731 on which other devices havebeen mounted in partial regions (device mounting regions 742 and 744 inFIG. 7C).

[A Process for Manufacturing a Composite Material Device]

FIGS. 8A to 8C show a structure of a semiconductor device 800manufactured using the method for manufacturing the semiconductor devicedescribed above. The semiconductor device 800 is a composite materialdevice manufactured by the above-described method for manufacturing. Thesemiconductor device 800) is manufactured by separating a semiconductorthin film layer island 808 forming a device structure on a base materialsubstrate from a base material substrate 801, bonding it to adestination substrate 831, and forming a wiring connected to the outsidethe semiconductor thin film layer. The example illustrated here is anexample and can be applied to semiconductor devices of various types,materials, and structures.

FIG. 8A shows a cross-section of the semiconductor device 800. In FIG.8A, the semiconductor thin film layer island 808, electrodes 822 and 824formed on the island 808, a fixing layer 814 having openings (816 a and816 b) at the electrode positions, an interiayer insulating film 842, awiring layer 854, and a wiring layer 856 are shown.

A device structure is formed by forming the electrodes 822 and 824, ordividing the semiconductor thin film layer into the semiconductor thinfilm layer island 808 (element separation) after forming thesemiconductor thin film layer on the base material substrate to form apredetermined device when manufacturing the semiconductor device 800.Thereafter, the fixing layer 814 is formed as shown in FIG. 8B. Further,a void 803 is formed at least between the base material substrate 801and the island 808. The void 803 is formed by etching away a region tobe removed.

Then, the island 808 is separated from the base material substrate 801after the pick-up substrate having the pick-up bump or the pick-up layermade of an organic material is coupled to partial regions of the island808 and the fixing layer 814. Thereafter, the separated island 808 isbonded to a predetermined position on the destination substrate 831. Thedestination substrate 831 may be made of a material different from thebase material substrate 801 and the island 808, for example. Surfaces tobe bonded (a bonding surface of the island and a surface of thedestination substrate) can be surface-treated for bonding prior to thebonding, if it is required. Another thin film layer, which is not shownin drawings, may be provided between the destination substrate 831 andthe island 808.

After bonding the island 808 to the destination substrate 831, openingsare formed at the positions of the electrode 822 and the electrode 824on the island 808 in the fixing layer 814 that is used as an interlayerinsulating film, as shown in FIG. 8C. Thereafter, the interlayerinsulating film 842 for forming a wiring is formed, and the wiring layer854 and the wiring layer 856 are formed to respectively couple with theelectrode 822 and the electrode 824, as shown in FIG. 8A. In this way,manufacturing of the semiconductor device 800, in which the fixing layer814 extends on the upper surface of the island 808 and the side surfacesof the island 808 on both sides in the first orientation, is completed.

As described above, according to the method for manufacturing thesemiconductor device of the present embodiment, the semiconductor thinfilm layer island having a device formed on the base material substratecan be favorably separated from the base material substrate and wellbonded to the destination substrate, thereby making it possible toobtain a composite material device having high performance and highreliability. The above method for manufacturing can be applied tovarious sizes and structures of the semiconductor thin film layerincluded in the semiconductor device. Since the pick-up bump made of anorganic material comprised of the pick-up substrate is manufactured by,for example, standard photolithography, an optimal pick-up substrate canbe easily prepared according to various changes in the form of thedevice structure and the semiconductor thin film layer and variouschanges in the form of the destination substrate. As described above,the method for manufacturing the semiconductor device according to thepresent embodiment easily enables optimal separation of thesemiconductor thin film layer from the base material substrate andoptimal bonding of the semiconductor thin film layer onto thedestination substrate.

[A Variation of the Shape of the Fixing Layer 110]

FIGS. 9A to 9D show variations of a shape of the fixing layer 110.

As shown in FIG. 9A, a width L2 b of the fixing layer 110 provided onthe base material substrate 101 and the width L2 b of the fixing layer110 covering the side surfaces of the semiconductor thin film layerisland 108 may be narrower than a width L2 a of a fixing layer coveringthe upper surface of the island 108. This enables easy separation of thefixing layer 110 provided on the island 108 from the fixing layer 110provided on the base material substrate 101 when detaching the island108 from the base material substrate 101 by using the pick-up substrate200.

In this case, as shown in FIG. 9B, the width L2 b of the fixing layer114 covering the shorter side surfaces of the semiconductor thin filmlayer island 108 is still narrower than the width L2 a of the fixinglayer 114 covering the upper surface in the composite material devicebonded to the destination substrate 301.

Further, as shown in FIG. 9C, regions 130 that cover portions of thelonger side surfaces of the semiconductor thin film layer island 108 andextend to the base material substrate 101 may be provided in the longerside regions of the fixing layer 110 that covers the semiconductor thinfilm layer island 108. At this time, the coverage of the longer sidesurfaces by the fixing layer 110 is preferably smaller than the coverageof the shorter side surfaces by the fixing layer 110. In this case, theregions 131 of the fixing layer 110 covering portions of the longer sidesurfaces of the semiconductor thin film layer island 108 are formed asshown in FIG. 9D in the destination substrate 301 to which thesemiconductor thin film layer island 108 is bonded. The coverage of thelonger side surfaces by the fixing layer 110 is smaller than thecoverage of the shorter side surfaces by the fixing layer 110 in thisstate.

[A Reduction of Lattice Defects in the Semiconductor Thin Film Layer104]

In the process of forming a GaN epitaxial layer on a Si wafer, a crystaldefect is sometime introduced into the semiconductor thin film layer 104due to i) a lattice mismatch between the material of the base materialsubstrate 101 and the material of the semiconductor thin film layer andii) a thermal expansion coefficient mismatch (difference in thermalexpansion coefficients) between the material of the base materialsubstrate 101 and the material of the semiconductor thin film layer.

A material having the same system as that of the semiconductor thin filmlayer may be used as the material of the base material substrate 101 tosolve such a problem. In this case, it becomes difficult to separate thesemiconductor thin film layer from the base material substrate 101 byetching, and therefore a semiconductor wafer, in which a differentmaterial layer having a large difference in etching rate with respect tothe materials of the base material substrate 101 and the semiconductorthin film layer 104 is provided between the base material substrate 101and the semiconductor thin film layer 104, can be used as the firstsubstrate. Further, a semiconductor wafer, in which a different materiallayer constituted by different materials having lattice constants andthermal expansion coefficients different from those of the base materialsubstrate 101 and the semiconductor thin film layer 104 is providedbetween the base material substrate 101 and the semiconductor thin filmlayer 104, may be used as the first substrate. For example, Si can beused as a material of the different material layer. In this case, theupper limit of the thickness of the different material layer providedbetween the base material substrate 101 and the semiconductor thin filmlayer 104 is preferably equivalent to the thickness of the semiconductorthin film layer 104.

The difference of the lattice constant between the base materialsubstrate 101 and the semiconductor thin film layer 104 is smaller thanthe difference of the lattice constant between the semiconductor thinfilm layer 104 and the different material layer, for example. Further,the difference of the thermal expansion coefficient between the basematerial substrate 101 and the semiconductor thin film layer 104 issmaller than the difference of the thermal expansion coefficient betweenthe semiconductor thin film layer 104 and the different material layer,for example.

If (1) the base material substrate 101 is, for example, a GaN substrate,(2) the different material layer is formed of, for example, Si(111), and(3) the semiconductor thin film layer 104 is formed of, for example,GaN, a downward warping stress (a stress causing the base materialsubstrate 101 to be bent to in a manner to protrude upward) may begenerated in the base material substrate 101, and an upward warpingstress (a stress causing the semiconductor thin film layer 104 to bebent in a manner to protrude downward) may bo generated, contrary to thebase material substrate 101, in the semiconductor thin film layer 104because the thermal expansion coefficient of GaN, which is 2.59 ppm, issmaller than the thermal expansion coefficient of Si(111), which is 5.59ppm. As described above, the stresses in opposite directions aregenerated in the base material substrate 101 and the semiconductor thinfilm layer 104, and so the base material substrate 101 and thesemiconductor thin film layer 104 can be made more resistant to warping.

Further, the upper limit of the thickness of the different materiallayer provided between the base material substrate 101 and thesemiconductor thin film layer 104 is preferably equivalent to thethickness of the semiconductor thin film layer 104. This enables theinfluence of the base material substrate 101 having a small thermalexpansion coefficient difference relative to the semiconductor thin filmlayer 104 to be dominant in the influence of a thermal stress of asubstrate (a laminated structure of the base material substrate 101 andthe thin different material layer) with respect to the semiconductorthin film layer 104 even if the thermal expansion coefficient of thedifferent material layer provided between the base material substrate101 and the semiconductor thin film layer 104 is different from thethermal expansion coefficient of the semiconductor thin film layer 104.Therefore, the influence of the thermal stress on the semiconductor thinfilm layer 104 of the different material layer can be suppressed to besmall. As a result, the lattice defects in the semiconductor thin filmlayer 104 can be reduced.

Furthermore, the etching rate of the different material layer for apredetermined etching method is greater than the etching rates of thebase material substrate 101 and the semiconductor thin film layer 104for the predetermined etching method. This makes it possible to form thevoid 103 efficiently by forming the region to be removed 106 of thedifferent material layer shown in FIG. 1C in addition to forming thesemiconductor thin film layer 104 with fewer lattice defects describedabove.

[A Variation of the Material of the Destination Substrate 301]

If a chip size of the semiconductor device is large, there is a problemthat heat distribution is generated in a chip according to the thermalconductivity of a substrate material which is a base of a semiconductordevice chip, and the temperature significantly rises in a central regionof the chip while the semiconductor device chip is operating. Inparticular, there is a problem that the temperature distribution becomeslarge if the thermal conductivity of the substrate to be the base of thesemiconductor device chip is small.

Therefore, a material having a thermal conductivity higher than thethermal conductivity of the base material substrate 101 may be selectedas a material of the destination substrate 301. For example, a ceramicsubstrate such as SiC, AlN, and SiN, a metal substrate such as Cu andAl, a composite metal material composed of a plurality of metals such asW, Cr, Cu, and Mo, a composite material substrate or a laminatedmaterial substrate containing a metal material layer and a ceramicmaterial, a substrate of a material containing carbon, or the like maybe used as the destination substrate 301. Making the thermalconductivity of the destination substrate 301 greater than the thermalconductivity of the base material substrate 101 allows manufacturing asemiconductor device which efficiently dissipates heat.

The temperature rise of the semiconductor device, constituted by aplurality of device elements, can be suppressed because the heatdissipation of the device element can be improved by dividing the deviceof semiconductor thin film layer into a plurality of device-clementislands and interconnecting the plurality of device elements formed ineach of the plurality of islands after the division with each other. Inparticular, the temperature rise of each device element can besuppressed even when the device is operated in large currents, by usinga material having a high thermal conductivity as the destinationsubstrate 301.

In manufacturing an integrated semiconductor device constituted by theplurality of device elements, the plurality of semiconductor thin filmlayer islands 108 formed on the base material substrate 101 may besimultaneously transferred to the destination substrate 301. Theintegrated semiconductor device, in which all device elements operateappropriately, can be manufactured by forming electrodes on theplurality of islands 108 transferred to the destination substrate 301 orby forming a wiring pattern for providing connections between at leastone pair out of the plurality of islands 108.

[Optimization of Crystal Orientation]

FIG. 10 schematically illustrates a semiconductor epitaxial wafer, inwhich a semiconductor epitaxial layer is formed on a wafer used as thebase material substrate 101. FIG. 10 shows a plurality of group IIInitride semiconductor thin film layer islands 108 formed on the Sisubstrate as the base material substrate 101. The orientation of theside of the island 108 is preferably within an angle range of ±45° orless with respect to the <112> orientation of the Si(111) substrate asthe base material substrate 101 in order to enable the group III nitridesemiconductor thin film layer island 108 to be detached from the basematerial substrate 101 in a good state. The orientation of the longerside of the island 108 is preferably the <112> orientation of theSi(111) substrate serving as the base material substrate 101.

Si(111) exhibits anisotropic etching properties for particular etchants.Utilizing the anisotropic etching properties of Si(111) allows theepitaxially grown semiconductor thin film layer on Si(111) to beseparated from Si(111) by removing the surface region of Si(111) byetching without etching away the entire wafer. The preferred orientationof the semiconductor thin film layer island 108 formed by beingepitaxially grown on the base material substrate 101 using Si(111) asthe base material substrate 101 has not been known so far. However, theinventor has found that it is preferable to set the orientation of oneside (for example, the longer side) of the island 108 within an anglerange of ±45° or less with respect to the <112> orientation of the Sisubstrate. The inventor has found that it is particularly preferable tomake the orientation of the longer side of the island 108 substantiallyparallel to the <112> orientation of the Si substrate.

Further, the inventor has found that, when the semiconductor thin filmlayer island 108 is formed of a hexagonal crystal, it is preferable toset the orientation of the longer side of the semiconductor thin filmlayer island 108 within an angle range of ±45° or less with respect tothe <1-100> orientation of a hexagonal crystal material like a group IIInitride semiconductor single crystal such as GaN. The inventor has foundthat it is particularly preferable to make the orientation of the longerside of the semiconductor thin film layer island 108 substantiallyparallel to the <1-100> orientation of the hexagonal crystal material.

As shown in FIG. 10 , the island 108 has a side having a length L3 and aside having a length L4. Although an example where the island 108 is arectangle whose side length L3 is longer than its side length L4 isshown below, the present invention can also be applied to a case whereL3=L4 (that is, where the island 108 is a square) by treating one of thesides as a longer side.

When the island 108 is a rectangle, it is preferable to form the island108 such that its side (longer side) having the length L3 issubstantially parallel to the <112> orientation of the Si(111)substrate. Here, “substantially parallel” means parallel within acertain error or variation range, and not significantly deviated fromparallel (for example, not exceeding ±10° with respect to parallel).

When crystal-growing the group III nitride semiconductor thin film layerhaving a C-surface ((0001) surface) on the Si(111) substrate, the <112>orientation of Si and the <1-100> orientation of the group III nitridesemiconductor thin film layer crystal become parallel. In this ease, itis preferable to form the island 108 such that the side of the island108 having the length L3 is substantially parallel to the <1-100>orientation of the group III nitride semiconductor epitaxial layercrystal.

As already described, it is possible to employ a plurality of methods asthe method for forming the island 108. For example, it is possible toform the semiconductor thin film layer island 108, in which theorientation of its one side is substantially parallel to the <1-100>orientation of the group III nitride semiconductor epitaxial layercrystal, by etching the crystal-grown semiconductor thin film layer.

Further, the semiconductor thin film layer island 108, in which theorientation of its longest side is substantially parallel to the <112>orientation of Si or the <1-100> orientation of the hexagonal crystal,may be formed by forming a mask layer having an opening by using aninorganic insulating film such as a SiCO₂ or Si_(x)N_(y) on the basesubstrate 101 and selectively growing the semiconductor thin film layerin the opening region. Moreover, the semiconductor thin film layerisland 108, in which the orientation of its longest side issubstantially parallel to the <112> orientation of Si or the <1-100>orientation of the hexagonal crystal, may be formed by crystal-growingthe selectively grown semiconductor thin film layer laterally on themask layer. The semiconductor thin film layer island 108 crystal grownon the mask layer has a high-quality crystal growth region that hasfewer defects than the semiconductor thin film layer crystal grown inthe region outside the mask layer.

According to an experiment conducted by the inventor, when the longerside (the side having the length L3) of the semiconductor thin filmlayer island 108 is set to be substantially parallel to the <110>orientation of the Si(111) substrate (that is, rotating the rectangleisland 108 shown in FIG. 10 by 90°), the etching of the Si(111)substrate surface directly below the device region (the semiconductorthin film layer island 108) did not proceed and the entire surface ofthe Si substrate directly below the island 108 could not be etched away.As a result, the islands 108 could not be detached from the Si(111)substrate used as the base material substrate 101 in a good state.

FIGS. 11A and 11B show a relation, investigated by the inventor in theexperiment, between i) an angle θ made by the orientation of the longerside of the semiconductor thin film layer island 108 and the <112>orientation of Si(111) or the <1-100> orientation of the hexagonalcrystal and ii) the etching rate of a Si(111) substrate surface regionin a direction perpendicular to the longer side of the semiconductorthin film layer island 108. The vertical axis of FIG. 11A shows a valueobtained by dividing the etching rate when θ=0°, 45°, and 90° by theetching rate when θ=0°. FIG. 11B is a figure for explaining the angle θ.

As shown in FIG. 11A, the etching rate for the direction perpendicularto the longer side is greatly reduced when the angle θ exceeds 45° andapproaches 90°. As shown in FIG. 11A, the angle θ made by theorientation of the longer side of the island 108 and the <112>orientation of Si(111) or the <1-100> orientation of the hexagonalcrystal preferably does not exceed at least 45° in order to well proceedthe etching between the island 108 and the Si(111) substrate and form avoid in the entire region between the island 108 and the Si(111)substrate that is directly below the island 108.

It can be confirmed from this result that the angle made by theorientation of the longer side (the side having the length L1) of therectangular island 108 and the <112> orientation of the Si(111)substrate is desirably set to be ±45° or less in order to detach theisland 108 from the Si(111) substrate in a good state by etching awaythe Si substrate surface over the entire surface directly below theisland 108 when etching away the surface region of the Si(111) substrateover the entire surface directly below the island 108.

If the semiconductor thin film layer is the hexagonal system crystalsuch as a group III nitride or SiC, the angle made by the orientation ofthe longer side (the length L3 in FIG. 10 ) of the rectangularsemiconductor thin film layer island 108 and the <1-100> orientation ofthe hexagonal crystal is desirably set to be ±45° or less. It should benoted that the semiconductor thin film layer island 108 may be made of amaterial having a hexagonal crystal system other than the III-nitridesemiconductor and SiC, for example, ZnO.

In the above description, the semiconductor thin film layer island 108has a rectangular shape, but if the semiconductor thin film layer island108 has another shape, the orientation of the longest side of thesemiconductor thin film layer island 108 may be substantially parallelto the <112> orientation of the Si(111) substrate (the orientation ofthe longest side is substantially parallel to the <1-100> orientation ofthe crystal of the semiconductor epitaxial layer).

FIG. 12 shows hexagonal semiconductor thin film layer islands 109provided on the base material substrate 101 of the Si(111) substrate.The island 109 has sides of lengths L1, L2, and L3, and satisfies therelationship of L1>L2 and L3. That is, the side having the length L1 isthe longest side. The side having the length L1 of the semiconductorthin film layer island 109 is substantially parallel to the <112>orientation of Si(111), as shown in FIG. 12 . In this case, when bondingthe semiconductor thin film layer island 109 constituted by thehexagonal crystal on the destination substrate 301, the orientation ofthe side having the length L1 (that is, the longest side) of thesemiconductor thin film layer island 109 is substantially parallel tothe <1-100> orientation of the hexagonal crystal.

It should be noted that the base material substrate 101 may be an SOI(Silicon on Insulator) substrate. Further, the base material substrate101 and the semiconductor thin film layer may be made of the samematerial. For example, if the semiconductor thin film layer is the groupIII nitride semiconductor, the base material substrate 101 may be a GaNsubstrate provided with a Si(111) layer thereon, for example. If the GaNsubstrate provided with the Si(111) layer thereon is the base materialsubstrate 101, GaN may be an insulating substrate (a semi-insulatingsubstrate or a high resistance substrate) or a conductive substrate (asubstrate doped with impurities).

As another example, the base material substrate 101 may be, for example,a substrate obtained by wafer bonding the Si(111) layer on a substratemade of an oxide material such as a quartz substrate or a sapphiresubstrate, a nitride material such as SiN or AlN, or a semiconductormaterial.

<Experimental Example>

FIG. 13A is a photomicrograph of a GaN semiconductor thin film layerisland formed on the Si(111) substrate as the base material substrate101. FIG. 13A is a photomicrograph of a state in which the surfaceregion of the Si(111) substrate, at least directly below thesemiconductor thin film layer island having a longer side in anorientation substantially parallel to the <112> orientation of Si(111)or substantially parallel to the <1-100> orientation of the GaNsemiconductor thin film layer, was etched away. A void is formed betweenthe semiconductor thin film layer island and the Si(111) substrate atleast in a region directly below the semiconductor thin film layerisland.

FIG. 13B is a photomicrograph of the GaN semiconductor thin film layerisland in which the orientation of the longer side of the semiconductorthin film layer island with respect to a crystal orientation of the basematerial substrate 101 is different from that shown in FIG. 13A. FIG.13B shows the GaN semiconductor thin film layer island that had passedthrough the process of etching the surface region of the Si(111)substrate at least directly below the semiconductor thin film layerisland having a longer side in an orientation substantiallyperpendicular to the <112> orientation of Si(111) or in an orientationsubstantially perpendicular to the <1-100> orientation of the GaNsemiconductor thin film layer. As shown in FIG. 13B, a region where novoid is formed remains between the islands of the semiconductor thinfilm layer and the Si(111) substrate, at least in the region directlybelow the semiconductor thin film layer island.

The etching time of the sample shown in FIG. 13B is about three timesthe etching time of the sample shown in FIG. 13A. A darkened regionindicated by (1) in FIG. 13B is the region where no void is formed inthe region directly below the semiconductor thin film layer island. Evenif the sample shown in FIG. 13B were to be etched for a considerablylong time, a region where no void is formed remains between thesemiconductor thin film layer island and the Si(111) substrate directlybelow the semiconductor thin film layer island, as shown in FIG. 13B.

The region indicated by (2) in FIG. 13B is a fixing layer. The regionindicated by (3) in FIG. 13B is a semiconductor thin film layer. In theregion indicated by (4) in FIG. 13B, it was found that etching damageoccurred in the semiconductor thin film layer island.

As described above, it was found from the inventor's experiment that theorientation of the longer side of the semiconductor thin film layerisland was desirably substantially parallel to the <112> orientation ofSi(111) or substantially parallel to the <1-100> orientation of thehexagonal crystal (the GaN semiconductor epitaxial layer) in order toform the void between the semiconductor thin film layer island and thefirst substrate in the entire region directly below the semiconductorthin layer island of the hexagonal crystal to separate the semiconductorthin layer island of the hexagonal crystal (for example, a stack of GaN,InN, AlN, GaN/Al_(x)Ga_(1-x)N/In_(x)Ga_(1-x)N, or the like and asemiconductor thin film layer of SiC, ZnO, or the like) from the firstsubstrate Si(111) substrate).

FIG. 14 is a photomicrograph of the semiconductor thin film layer islandbeing bonded to the destination substrate 301 in the experimentperformed by the inventor. The longer side of the semiconductor thinfilm layer shown in FIG. 14 is substantially parallel to the <1-100>orientation. There is a portion of the fixing layer 114 (a fixing layercovering partial regions of the upper surface and the shorter sidesurfaces of the semiconductor thin film layer island), which remains onthe semiconductor thin film layer, as shown in FIG. 14 .

In the photomicrograph shown in FIG. 14 , neither interference fringesnor color unevenness are seen on the semiconductor thin film layerisland bonded to the destination substrate 301, and it is confirmed thatthe semiconductor thin film layer island was well bonded to thedestination substrate 301. The semiconductor thin film layer island canbe bonded to the destination substrate 301 in a good state in this wayfor the following reasons: (1) the semiconductor thin film layer islandis formed such that the orientation of the longer side of thesemiconductor thin film layer island is substantially parallel to the<1-100> orientation, (2) the void is formed between the semiconductorthin film layer island and the base material substrate 101 at least inthe region directly below the semiconductor thin film layer island, and(3) damage due to the etching process is not caused on the surface ofthe semiconductor thin film layer facing the void. Further, it is alsoconsidered that the semiconductor thin film layer island can be bondedto the destination substrate 301 in a good state because thesemiconductor thin film layer island can be separated from the basematerial substrate 101 in a good state by separating the semiconductorthin film layer island from the base material substrate 101 in a statewhere the void is formed in the region directly below the semiconductorthin film layer island.

[A Method for Easily Breaking the Fixing Layer 110]

FIGS. 15A and 15B are figures for explaining a method for easilybreaking the fixing layer. As shown in FIG. 15A, a void 117 may beformed over a region wider than the void 103 shown in FIG. 1E in theetching process for forming the void between the semiconductor thin filmlayer island 108 and the base material substrate 101. The void 117 isformed between the fixing layer 110 and the base material substrate 101in a partial region where the fixing layer 110 is formed on the basematerial substrate 101 in the example shown in FIG. 15A.

If a downward force is applied to the fixing layer 110 in this state, alarge stress is applied to corners (ellipse portions indicated by abroken line in FIG. 15A) of the region, in the fixing layer 110, wherethe void 117 exists between the fixing layer 110 and the base materialsubstrate 101, resulting in easy cracking or breaking at the broken lineportions shown in FIG. 15B.

FIG. 16 is a photomicrograph showing results of observing a separationstate of the fixing layer 110 in an actual experiment. FIG. 16 is aphotomicrograph of the back surface (the surface to be bonded) of thesemiconductor thin film layer island 108 separated from the basematerial substrate 101. There is a fixing layer 110 coating partialregions of the side surfaces of the semiconductor thin film layer island108 at a portion indicated by “A” in FIG. 16 . FIG. 16 shows the backsurface of the semiconductor thin film layer island and the uppersurface of the fixing layer 110 is hard to see, but the fixing layer 110having the width indicated by a bracket in the vicinity of A in FIG. 16extends from the side surface “a” of the semiconductor thin film layerisland 108 to the side surface “b” through the upper surface (thesurface opposite to the surface visible in FIG. 16 ) of thesemiconductor thin film layer island 108.

As can be seen in FIG. 16 , there is no fixing layer 110 extending fromside surface of the semiconductor thin film layer island 108 to theoutside of the semiconductor thin film layer island 108. Further, thefixing layer 110, extending beyond the height of the back surface (thesurface observed by a microscope) of the semiconductor thin film layerisland 108 shown in FIG. 16 , is not seen.

FIG. 17 is a photomicrograph of a state where the semiconductor thinfilm layer island 108 separated from the base material substrate isbonded to the destination substrate 301. A portion of the fixing layer110 remains on the upper surface and side surfaces of the semiconductorthin film layer island 108 shown in FIG. 17 . The semiconductor thinfilm layer island 108 separated from the base material substrate 101 waswell bonded to the destination substrate 301 as shown in FIG. 17 .

Although the fixing layer provided on the semiconductor thin film layerisland 108 is formed at a position shifted slightly upward from thecenter line of the semiconductor thin film layer island 108 in thephotomicrographs shown in FIGS. 16 and 17 , the fixing layer 110 may beformed on the semiconductor thin film layer island 108 on the centerline or at a position shifted from the center line of the semiconductorthin film layer island 108. Further, the fixing layer 110 may be formedin an orientation oblique to the center line of the island 108.

The fixing layer 110 may have a region extending in the transverseorientation corresponding to the second orientation from at least aportion of the region extending in the longitudinal orientationcorresponding to the first orientation. FIGS. 18A and 18B show examplesof the fixing layer 110 having a region extending in the transverseorientation. The fixing layer 110 shown in FIG. 18A has regionsextending on both sides of the fixing layer 110 from the samelongitudinal position. The fixing layer 110 shown in FIG. 18B hasregions extending on both sides from different longitudinal positions ofthe fixing layer 110.

[Formation of a Step Structure on the Semiconductor Thin Film Layer]

When forming the device structure in the semiconductor thin film layer,a step is formed in the semiconductor thin film layer in accordance withthe function of the device structure. FIGS. 19A and 19B schematicallyshow a state where the semiconductor thin film layer formed on the basematerial substrate 1001 is divided into individual semiconductor thinfilm layer island 1002. FIG. 19A is an overhead view of the basematerial substrate 1001 and the semiconductor thin film layer island1002, and FIG. 19B shows a cross section of these portions. Thesemiconductor thin film layer island 1002 has a plurality of regions(1002 a and 1002 b) having different heights.

In the process of etching away the surface of the base materialsubstrate 1001 on which the semiconductor thin film layer island 1002 isformed to separate the semiconductor thin film layer island 1002 fromthe base material substrate, the periphery of the region 1002 b in ihebase material substrate 1001 is also etched away since the region 100 bis thinner than the region 1002 a. Since the alignment accuracy of amask opening part when forming a resist mask opening part prior to theetching is not ±0, a deviation occurs between the mask opening part andthe outer peripheral line of the island 1002. Therefore, in order tosecure a margin, the outer peripheral line of the resist mask openingpart is required to be located outside the outer peripheral line of theisland 1002. Consequently, a groove 1003 is formed in a region aroundthe region 1002 b as shown in FIG. 19B.

When the groove 1003 is formed, an area of a side surface region of thebase material substrate 1001 directly below the region 1002 b exposed tothe region of the groove 1003 becomes larger than the area of the sidesurface region of the base material substrate 1001 directly below theregion 1002 a. Consequently, a partial region (the region directly belowthe region 1002 b) of the base material substrate 1001 having a largeside surface contacting the etchant is etched away faster, therebygenerating a step in the base material substrate 1001 directly below theregion 1002 b. The step directly below the semiconductor thin film layerisland 1002 causes a problem that the semiconductor thin film layerisland bends at an acute angle and cracks when pushing the semiconductorthin film layer island downward (a direction toward the base materialsubstrate). Therefore, in order to solve such a problem, forming a stepstructure that is not exposed to the outer periphery of thesemiconductor thin film layer in the process of forming thesemiconductor thin film layer is suitable for the method formanufacturing the semiconductor device by separating the semiconductorthin film layer from the base material substrate.

FIGS. 20A to 20C show a semiconductor device including a semiconductorthin film layer island 920 including a step structure that is notexposed to the outer periphery of the semiconductor thin film layerisland. FIG. 20A is an overhead view of the semiconductor device. FIG.20B shows an A-A-line cross section of the semiconductor device, andFIG. 20C shows a B-B-line cross section of the semiconductor device. InFIGS. 20A to 20C, the semiconductor thin film layer island 920 is bondedto the destination substrate 931, the semiconductor thin film layerisland 920 is including a region 921 where a p-type semiconductor layeris exposed on the surface, a concave region 922 where an n-typesemiconductor layer is exposed on the surface, and an outer peripheralwall 923 where the p-type semiconductor layer is exposed on the surface.

FIGS. 21A to 21I are figures lor explaining the method for manufacturingthe semiconductor device shown in FIGS. 20A to 20C. Here, an LEDstructure is described as an example, but the present manufacturingmethod is not limited to a method for manufacturing a semiconductordevice having the LED structure, and can be applied to a method formanufacturing a semiconductor device having various device structures.

The base material substrate 901 in FIG. 21A is a base material substratefor epitaxially growing an LED semiconductor layer (for example, alaminated structure of the group III nitride semiconductor layer such asGaN) and is, for example, a Si substrate. Regions indicated by brokenlines in FIG. 21A are regions where a plurality of semiconductor thinfilm layer islands 920 are to be formed.

FIG. 21B is an A-A-line cross section of FIG. 21A. As shown in FIG. 21B,the semiconductor thin film layer island 920 has the region 921 wherethe p-type semiconductor layer is exposed on the surface, the region 922where the p-type semiconductor layer is exposed on the surface byetching away the p-type semiconductor layer, and the outer peripheralwall 923 where the p-type semiconductor layer is exposed on the surface.

As shown in FIG. 21C, the semiconductor thin film layer is divided intoindividual semiconductor thin film layer islands 920 on the basematerial substrate 901. Subsequently, a fixing layer 928 is formed suchthat at least a portion of the semiconductor thin film layer island iscoupled to the base material substrate 901. Here, the portion of thesemiconductor thin film layer island is at least some regions of theregion 921 where the p-type semiconductor layer is exposed, the region922 where the n-type semiconductor layer is exposed, and a surface ofthe outer peripheral wall 923. FIG. 21D is a cross section of theperiphery of the island 920 formed by the division (A-A cross section ofFIG. 21C) and shows a state where the fixing layer 928 for coupling theisland 920 to the base material substrate 901 is formed. FIG. 21C showssix semiconductor thin film layer islands 920, but the number, pitch,shape, size, and the like of the semiconductor thin film layer islands920 can be appropriately designed. An outer peripheral wall 923 isprovided to the region 922 where the n-lype semiconductor layer isexposed such that a step is not exposed on the outer periphery of thesemiconductor thin film layer island 920, and so no step reflecting thedevice structure of the semiconductor thin film layer island 920 isformed in the base material substrate 901 region around thesemiconductor thin film layer island 920.

A standard photolithography and etching process can be applied in theprocess of forming the semiconductor thin film layer island 920 byetching a region of the semiconductor thin film layer other than theregion where the semiconductor thin film layer island 920 is to beformed. Though not shown in drawings, after this process, an electrodecontact may be formed in a partial region of the surface of the region921 where the p-type semiconductor layer is exposed and in a partialregion of the surface of the region 922 where the n-type semiconductorlayer is exposed. In the formation of the electrode contact, forexample, a metal thin film layer capable of forming an ohmic contact isformed, and an electrode contact sintering process can be appropriatelyperformed in order to form an electrode contact having a low resistance.

Subsequently, at least the surface region of the base material substrate901 directly below the semiconductor thin film layer island 920 isremoved by etching, as shown in FIG. 21E. In the process of etching awaythe surface region of the base material substrate 901 directly below thesemiconductor thin film layer island 920, it is desirable to use anetchant or etching gas whose etching rate for the surface region of thebase material substrate 901 is higher than that for the semiconductorthin film layer. A void (a shaded region in FIG. 21E) between thesemiconductor thin film layer island 920 and the base material substrate901 is formed in this etching process.

Subsequently, the semiconductor thin film layer island 920 is separatedfrom the first substrate as shown in FIG. 21F. Though not shown indrawings, a structure (for example, the pick-up substrate describedabove) for temporarily adhering or adsorbing the semiconductor thin filmlayer island can be used in this process. In the example shown in FIG.21F, a portion of the fixing layer 928 remains on the base material 901after the island 920 is separated.

Subsequently, the semiconductor thin film layer island 920 separatedfrom the base material substrate 901 is bonded onto the destinationsubstrate 931 as shown in FIG. 21G. In the process of bonding thesemiconductor thin film layer island 920 onto the destination substrate931, the semiconductor thin film layer island 920 is pressed onto thedestination substrate 931 without using an adhesive. Prior to theprocess of bonding the semiconductor thin film layer island 920 onto thedestination substrate 931, a surface treatment process may be performedon the surface of the semiconductor thin film layer island 920 to bebonded and the surface of the destination substrate 931. Although notshown in drawings, another material layer may be provided between thesemiconductor thin film layer island 920 and the destination substrate931 (at least a region directly below the semiconductor thin filmlayer). The bonding without an adhesive is desirable in the process ofbonding the semiconductor thin film layer island 920 to the destinationsubstrate 931, but a paste or a sheet containing the adhesive may beused for bonding.

Subsequently, a structure required for the semiconductor device such asan interlayer insulating film and wiring is formal as shown in FIG. 21Hafter bonding the semiconductor thin film layer island 920 to thedestination substrate 931. If, for example, sintering for lowering thecontact resistance between the electrode and the surface of thesemiconductor thin film layer island 920 is not required or thesintering temperature is low, after bonding the semiconductor thin filmlayer island 920 to the destination substrate 931, an aperture is formedin the fixing layer 928, an electrode 924 is formed in the region 921where the p-type semiconductor layer is exposed in the aperture, anelectrode 925 is formed in the region 922 where the n-type semiconductorlayer is exposed, and a wiring layer 927 that connects the electrode 924and the electrode 925 is formed. Further, an interlayer insulating film926 containing a portion of the above-described fixing layer 928 may beformed. For example, the interlayer insulating film 926 may be providedon the portion of the fixing layer 928.

When the plurality of islands 920 is bonded to the destination substrate931, the electrode 924 and the electrode 925 formed on each of theplurality of islands 920 may be connected by the wiring layer 927. Theplurality of islands 920 may be obtained by dividing one singlesemiconductor device having a predetermined size into a plurality ofsmall element semiconductor devices (a plurality of small islands). Theplurality of small element semiconductor devices may all have the samestructure and may all have the same size. This enables suppression ofthe temperature rise as follows.

One large semiconductor device generates a large amount of heat duringoperation, and in particular, the heat generated in the central regionthereof is poorly dissipated, resulting in a large temperature rise inthe central region. In contrast, if one single semiconductor device isdivided into a plurality of small element semiconductor devices, thedivided element semiconductor devices have small sizes and each elementsemiconductor device is connected by a wiring layer 927 of a metalmaterial having high thermal conductivity, and so the heat generated ineach element semiconductor device is efficiently dissipated through thedestination substrate 931 and the wiring layer 927. As a result, thetemperature rise of each small element semiconductor device issuppressed.

Further, since the plurality of element semiconductor devices, which isa semiconductor thin film layer, is bonded onto the destinationsubstrate 931, each small size element semiconductor device can beconnected by the metal thin film wiring layer, which enables highdensity integration. As a result, a compact semiconductor device can beobtained even when one semiconductor device is divided into a pluralityof element semiconductor devices. Such a configuration is particularlysuitable for a semiconductor device that allows a large current to flow,for example, a power semiconductor device using semiconductor materialssuch as Si, SiC, GaN, Ga₂O₃, and diamonds.

In the method for manufacturing the semiconductor device described whilereferencing FIGS. 21A to 21H, the fixing layer 928 is formed in FIG.21D, but the process subsequent to FIG. 21E may be performed withoutforming the fixing layer 928. In this case, for example, the island 920may be separated from the base material substrate 901 through thefollowing steps as shown in FIG. 21I: (1) forming the void indicated bythe shaded region while fixing the pick-up substrate 930 on the surfaceof the island 920 (for example, the surfaces of the region 921 where thep-type semiconductor layer is exposed and the outer peripheral wall923), and (2) pulling up the pick-up substrate 930 after forming thevoid. In the condition of FIG. 21I, the island 920 may be fixed by anexternal device other than the pick-up substrate 930.

Thus, when the fixing layer 928 is not formed, the electrode 924 isformed in the region 921 where the p-type semiconductor layer is exposedand the electrode 925 is formed in the region 922 where the n-typesemiconductor layer is exposed after bonding the semiconductor thin filmlayer island 920 to the destination substrate 931. Further, i) theinterlayer insulating film 926 covering some regions of the region 921where the p-type semiconductor layer is exposed and the region 922 wherethe n-type semiconductor layer is exposed as well as having an openingwhere portions of the electrode 924 and the electrode 925 are exposedand ii) the wiring layer 927 connecting the electrode 924 and theelectrode 925 are formed.

The present invention is explained on the basis of the exemplaryembodiments. The technical scope of the present invention is not limitedto the scope explained in the above embodiments and it is possible tomake various changes and modifications within the scope of theinvention. Further, new exemplary embodiments generated by arbitrarycombinations of them are included in the exemplary embodiments of thepresent invention. Further, effects of the new exemplary embodimentsbrought by the combinations also have the effects of the originalexemplary embodiments.

What is claimed is:
 1. A method for manufacturing a semiconductor devicein which a semiconductor thin film layer formed on a first substrate isseparated from the first substrate and bonded onto a second substratedifferent from the first substrate, the method comprising the steps of:forming a fixing layer that is a thin film for coupling at least aportion of a main surface of the semiconductor thin film layer on theside opposite to a first substrate side and at least a portion of thesurface of the first substrate on a semiconductor thin film layer side;coupling a third substrate different from the first substrate and thesecond substrate to the coupling region that is at least portions of thefixing layer and the semiconductor thin film layer; separating thesemiconductor thin film layer from the first substrate by moving thethird substrate away from the first substrate with the third substratecoupled to the coupling region; and bonding the semiconductor thin filmlayer to the second substrate after separation from the first substrate,wherein the forming the fixing layer forms the fixing layer having athickness such that a crack is generated between the fixing layer formedon the first substrate and the fixing layer formed on a side surface ofthe semiconductor thin film layer by a force for moving the thirdsubstrate.
 2. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the forming the fixing layer forms thefixing layer having a thickness such that the fixing layer is cut off bya force for moving the third substrate in a direction away from thefirst substrate.
 3. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the forming the fixing layer forms thefixing layer having a thickness such that a crack is generated in thefixing layer due to the force for moving the third substrate toward thefixing layer in the coupling is applied.
 4. The method for manufacturinga semiconductor device according to claim 1, wherein the forming thefixing layer forms the fixing layer having a thickness smaller than thethickness of the semiconductor thin film layer.
 5. The method formanufacturing a semiconductor device according to claim 1, furthercomprising the step of: forming a void by removing a partial region ofthe semiconductor thin film layer or the first substrate, or a partialregion of a layer between the semiconductor thin film layer and thefirst substrate between the forming the fixing layer and the coupling.6. The method for manufacturing a semiconductor device according toclaim 1, further comprising: separating the semiconductor thin filmlayer front the third substrate by removing an organic material layerincluded in the third substrate and coupled to the second substrateafter the bonding the semiconductor thin film layer to the secondsubstrate.